After an exhaustive search, I can't find any chatter about the pros and cons of the 4.8 liter versus the 6.0 liter engine in the Chevrolet Express based "B"s. Does the 6.0 with the Allison get better or poorer gas mileage, all other considerations being equal. I typically drive the blue roads, so interstate driving is not much of an issue. I am specifically looking at a Roadtrek on the Chevy chassis. Also, is there any chatter about any of the big manufacturers starting to use a small diesel in their vans?(I do know about the Mercedes) decisions decisions decisions.
Thanks for any information,
Topo

You want to go with the engine and transmission combination that has the most torque. Torque relates to pulling power so the more torque you have the less throttle you'll need to use taking off from a dead stop or going up a hill. That helps reduce fuel consumption.

The Chevy Express and the GMC Savanna don't come with the Allison transmission. It won't fit. It uses the same 6spd HydraMatic that goes in the 1500 and 2500/3500HD gas model GM pickups.
The vans can be bought with the Duramax, but don't know if Roadtrek offers it.

Yep. My friend-mechanic's jaw literally dropped when he looked under the Tiger and saw the size of the 6-speed Allison... his actual words are unprintable here, but amounted to 'Darn, that's a BIG transmission!'

But on the back roads around here, I'd definitely prefer any 6 speed, including the Hydramatic, over the standard GM 4 speed. There are too many situations where the 4 speed doesn't have quite the right ratio to be comfortable.

We are Blue Roaders, too. We also spend a month or more in the Rockies every year. Our 6.0 on the 210RT has always served us well. I am not a mechanical genius and all I want is something that works well and serves my purposes. We travel with a full load of gear and water, two people and Sally Ann the Wonder Dog.

All I can tell you is we make the passes at 12000 feet routinely and never have problems. We are looking around and not trying to go at 60 miles an hour and we use lower gears and lock out the OD. No problems. Had this rig for six years and am perfectly happy. I calculate our mileage to be about 14+ on the Interstates at the speed limits. Around here, that is 70 or 75 mph with the AC usually running (102 yesterday). I suspect if I dropped back to 60ish we would get over 15 mpg. We use the Interstates just to get to the Blue.

All that said, I wouldn't want a smaller engine. Prior to this rig we had a 96 RT190P Dodge with the 5.2 and it worked fine, but pulled down pretty good on the passes. But it was fine with us and we got about 15+ on it most of the time. I still miss that rig......lots of fun places and great memories.

There is a lot going on to improve light truck fuel efficiency and this will be a major update.

Ford's Ecoboost tech is pretty good stuff.

I think direct injection, turbochargers, regenerative braking, mild hybrid tech are the low hanging fruit as the mfrs head towards meeting the 2016 CAFE average of 34.1 mpg and the 2025 average of 54.5 mpg.

There will always be trucks sold that can meet what the application requires.

If I were getting a Chevy chassis B, I would only consider the 6.0. I suppose the 4.8 would be fine if the B was going to spend it's life only on flat land. I wouldn't want the 4.8 if I were going to travel in the western mountains. Would't want it in some places in the eastern mountains.

Topophillia wrote:After an exhaustive search, I can't find any chatter about the pros and cons of the 4.8 liter versus the 6.0 liter engine in the Chevrolet Express based "B"s. Does the 6.0 with the Allison get better or poorer gas mileage, all other considerations being equal. I typically drive the blue roads, so interstate driving is not much of an issue. I am specifically looking at a Roadtrek on the Chevy chassis. Also, is there any chatter about any of the big manufacturers starting to use a small diesel in their vans?(I do know about the Mercedes) decisions decisions decisions.
Thanks for any information,
Topo

I have had a 2012 RT 170 (4.8 L) for only a couple of months. For most areas, it does great. However, I have a road and driveway with about a 25 degree incline from a flat area where I have to take off at 0 mph...I have tried 2nd gear, drive, and 1st...it lugs at all. If I had to do this over, I would go with the 6.0.

When I was shopping for my Roadtrek I was advised by many to avoid the smaller engine and go with the 6.0L engine. There is a lot of weight in the Roadtrek and you want an engine that you do not have to be concerned won't keep you able to pass and handle inclines without a problem. There was not that much difference in price. My Roadtrek 190 is built in a Chevy 3500 Express van and it is now standard with a six speed transmission. The new ones also run on Flex Fuel BUT the generator prevents you from using Flex Fuel in the van.

The best mileage that I have had so far was just under 20 mpg with all limited access road driving at 65 mph. It gets about 15 to 16 with local road driving and averages between 17 and 18. Not bad.

The only diesel choices that I have seen on Class B's are Sprinters - now Mercedes (formerly tagged Dodge). You will get higher mpg with a diesel Sprinter.

bobojay5 wrote:The Chevy Express and the GMC Savanna don't come with the Allison transmission. It won't fit. It uses the same 6spd HydraMatic that goes in the 1500 and 2500/3500HD gas model GM pickups.
The vans can be bought with the Duramax, but don't know if Roadtrek offers it.

To expand on my earlier comment, the transmission that's used is either the Turbo Hydramatic 6L80 or 6L90. Even the Duramax vans don't come with the Allison.

We had a 2006 Chevy PleasureWay Lexor, (equivalent to a Roadtrek 190P), that had the 6.0, with the 4spd auto. GLAD we had the 6.0, and would have loved to have the 6spd of today in it.